1. Field of the Invention
The present invention relates to optical disc devices and hybrid optical discs, and, in particular, to a hybrid optical disc in which a DVD layer and a next generation DVD layer are arranged in sequence from a laser light entering side, and an optical disc device suitably used in reproducing the same.
2. Description of the Related Art
Presently, standardization of the next generation DVD (Digital Versatile Disc) using a blue laser light having a wavelength of about 405 nm is being put forward. In such standardization, consideration is made on arranging two recording layers, which are the recording layer corresponding to the blue laser light (hereinafter referred to as “HDDVD layer”) and the recording layer corresponding to the red laser light (hereinafter referred to as “DVD layer”), in the stacking direction.
In the next generation DVD (hereinafter referred to as “hybrid next generation DVD”), the DVD layer is positioned first when seen from the laser light entering side. The same format as that for the existing DVD is applied to the DVD layer. The information indicating that the HDDVD layer additionally exists behind the DVD layer is not held in the DVD layer. Therefore, when drawing process is performed on the DVD layer, the disc is handled as a DVD with a single recording layer.
Japanese Laid-Open Patent Publication No. 2003-346348 discloses an optical disc having two recording layers and a driving device for the same.
The driving device is normally designed to perform the drawing process on the recording layer positioned first when seen from the optical pick up side. The reproduction process is performed on the relevant recording layer if the lead-in information can be read from the recording layer. When the hybrid next generation DVD is loaded on this type of driving device, reproduction on the DVD layer arranged on the optical pick up side is carried out. However, the information indicating that the HDDVD layer is present is not held in the DVD layer, as mentioned above. Thus, the reproduction process similar to that when the DVD of single layer type is loaded is performed on the driving device side. In this case, the reproduction of the HDDVD layer may be missed although the HDDVD layer that may provide high capacity content is present.